Hi,
I'm currently rewriting some of my views in Erlang because I've had trouble
with a few large documents exploding up the javascript interepreter and that's
a good excuse to switch to Erlang and gain some extra performance too.
I have one view which is rather complex and which contains 2 dictionaries
(hashes, objects, whatever you want to call them) each of around 150 elements.
These are used to remap some of the data from one form to another. Every 6
months or so I need to add a couple of new entries to these and in the past
that has meant rebuilding the whole view which takes a few days. That's all ok
but I'm wondering how best to deal with this now I'm reimplementing in Erlang.
Firsly I'm not sure of the efficiencies of doing something like this:
Fun({Doc}) ->
Lookup1 = [{<<"foo">>,<<"bar">},{<<"baz">>,<<"wibble">>},....],
%% Rest of the code which actually uses Lookup1
OldVal = proplist:get_value(<<"to_remap">>, Doc),
NewVal = proplist:get_value(OldVal, Lookup1),
Emit(NewVal, something...)
end.
Will Lookup1 get recreated every time a document is processed by the view, or
every time the view updater is kicked, or something else?
My example shows a proplist. It sounds like I should actually use a dict
structure. It looks like I can pass in the same list but run it through
dict:from_list/1. That's all fine but my questions about efficiency apply even
more.
Should/Can I keep this data outside of the view code? I fully understand the
need to detect changes which alter the view output but in this case I can
actually cheat by promising to only ever add entries, and to always add entries
to the dictionary prior to adding and documents which require the change.
Obviously I would need to tread very carefully but I could read the data from a
file somewhere on disk... or maybe even from another document in the database.
Thanks,
Paul
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